The present invention is in the field of pharmaceuticals. In particular, it is related to the field of anti-angiogenic pharmaceuticals for the prevention and treatment of disease.
Angiogenesis is the process through which new vascular structures arise by outgrowth from pre-existing capillaries. In this process, endothelial cells become detached from the basement membrane as this support is degraded by proteolytic enzymes. These cells then migrate out from the parent vessel, divide, and form into a newly differentiated vascular structure (Risau, (1997) Nature 386:671-674; Wilting et al., (1995) Cell. Mol. Biol. Res. 41(4):219-232). A variety of different biological factors have been found to function in controlling blood vessel formation (Bussolino et al., (1997) Trends in Biochem Sci 22(7):251-256; Folkman and D""Amore, (1996) Cell 87:1153-1155). These include proteins with diverse functions such as growth factors, cell surface receptors, proteases, protease inhibitors, and extracellular matrix proteins (Achen and Stacker, (1998) Int. J. Exp. Pathol. 79:255-265; Devalaraja and Richmond, (1999) Trends in Pharmacol. Sci. 20(4):151-156; Hanahan, (1997) Science 277:48-50; Maisonpierre et al, (1997) Science 277:55-60; Suri et al, (1996) Cell 87:1171-1180; Sato et al, (1995) Nature 376:70-74; Mignatti and Rifkin, (1996) Enzyme Protein 49:117-137; Pintucci et al., (1996) Semin Thromb Hemost 22(6)517-524; Vernon and Sage, (1995) Am. J. Pathol. 147(4):873-883; Brooks et al., (1994) Science 264:569-571; Koch et al., (1995) Nature 376:517-519). The complexity of the angiogenic process and the diversity of the factors that control its progression provide a useful array of points for therapeutic intervention to control vascular formation in vivo.
Angiogenesis normally occurs in a carefully controlled manner during embryonic development, during growth, and in special cases such as wound healing and the female reproductive cycle (Wilting and Christ, (1996) Naturwissenschaften 83:153-164; Goodger and Rogers, (1995) Microcirculation 2:329-343; Augustin et al., (1995) Am. J. Pathol. 147(2):339-351). Some of the important steps in the process of angiogenesis are: 1) growth factor (i.e. vascular endothelial growth factor, VEGF) signaling; 2) matrix metalloproteinases (MMP) and VEGF receptor interaction; 3) endothelial cell migration to site of growth factor signaling; and 4) endothelial cell tubule formation. Pathological angiogenesis play a central role in a number of human diseases including tumor growth and metastatic cancer, diabetic retinopathy, rheumatoid arthritis, and other inflammatory diseases such as psoriasis (Folkman, (1995) Nature Med. 1(1):27-31; Polverini, (1995) Rheumatology 38(2):103-112; Healy et al., (1998) Hum. Reprod. Update 4(5):736-396). In these cases, progression of disease is driven by persistent unregulated angiogenesis. For example, in rheumatoid arthritis, new capillary blood vessels invade the joints and destroy the cartilage. In diabetic retinopathy, capillaries in the retina invade the vitreous, bleed and cause blindness. In diabetic retinopathy, capillaries in the retina invade the vitreous, bleed and cause blindness. Significantly, tumor growth and metastisis are angiogenesis dependent. Most primary solid tumors go through a prolonged avascular state during which growth is limited to approximately 1-2 mm in diameter. Up to this size, tumor cells can obtain the necessary oxygen and nutrient supply by passive diffusion. These microscopic tumor masses can eventually switch on angiogenesis and recruit surrounding blood vessels to begin sprouting capillaries that vascularize the tumor mass, providing the potential for continuing expansion of the tumor and metastasis of malignant cells to distant locations. Although significant progress has been made in understanding the biological events that occur during pathological angiogenesis, there are presently no effective pharmaceutical compounds that are useful for controlling angiogensis in vivo. Thus, effective therapies capable of controlling angiogenesis have the potential to alleviate a significant number of human diseases.
Traditionally, pharmaceutical compounds have been developed by screening synthetic chemical compounds for desirable pharmaceutical properties and then testing them for toxicity and effectiveness in vivo. Compounds selected this way frequently have toxic side effects in vivo and this approach has not been successful in developing effective angiogensis inhibitors for disease therapy. More recently, techniques of molecular biology have been applied to develop angiogenesis inhibitors. Protein inhibitors of angiogenesis such as angiostatin (O""Reilly et al., (1994) Cell 79(2):315-328) and endostatin (O""Reilly et al., (1997) Cell 88(2):277-285), that control vascular formation in experimental models, have been discovered. Nevertheless, such protein therapeutics are expensive to produce and have been found to be difficult to formulate and deliver in subjects. At present, protein angiogensis inhibitors have yet to be developed into therapeutic pharmaceuticals for disease patients. Thus, there exists a need for therapeutic compounds that can be safely administered to a patient and be effective at inhibiting the pathological growth of vascular endothelial cells. The present invention provides compositions and methods that are useful for this purpose and provides related advantages as well.
Gossypol and its derivatives have been found to inhibit growth and proliferation of endothelial cells and the process of vascularization. Thus, this invention provides methods for inhibiting the proliferation of endothelial cells, and in particular cells that are dividing to a pathological degree or in a tissue. This invention also provides a method to inhibit neovascularization in tissue. Each method requires delivering to the cell or tissue an effective amount of gossypol, or a pharmaceutically acceptable salt, derivative or prodrug thereof.
Also provided herein is a method for treating a disease associated with hyperproliferation of endothelial cells and/or neovascularization by administering to a subject an effective amount of gossypol, or a pharmaceutically acceptable salt, derivative or prodrug thereof. Kits to treat patients are provided as well.
Further provided is a screen for identifying new therapeutic agents that have the same, similar or better therapeutic effect as gossypol, or a pharmaceutically acceptable salt, derivative or prodrug thereof. The screen requires comparing the antiproliferative effect of gossypol, or a pharmaceutically acceptable salt, derivative or prodrug thereof, with the agent.